OracleORA-02291

ORA-02291: Integrity Constraint Violated — Parent Key Not Found

ORA-02291 is the Oracle foreign key constraint error raised when a child record references a parent key value that does not exist in the parent table.

Example Query

INSERT INTO orders (order_id, customer_id)
VALUES (1, 9999);
-- No customer with id 9999 exists

Common Causes

  1. 1Parent record not yet inserted when child record is created
  2. 2Wrong foreign key value due to a data mapping error
  3. 3Parent record deleted without cascading to child records

How to Fix It

Insert parent records before child records. Verify the parent key exists: SELECT * FROM customers WHERE customer_id = 9999. Define ON DELETE CASCADE if child records should be removed with the parent.

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